The invention relates to a thread guide for drawing threads overhead from two yarn bobbins disposed coaxially one above the other, a separate thread guide flyer arrangement journalled by means of a respective bearing bushing being provided for each yarn bobbin.
In a thread guide of this kind which is described in German Patent Specification (Auslegeschrift) No. 11 59 826 and which is provided for a two-for-one twisting spindle, the thread guide flyer arrangement associated with the lower yarn bobbin is mounted on the spindle axis between the two yarn bobbins, while the second thread guide flyer arrangement provided for the upper yarn bobbin is also rotatably mounted on the axis of the spindle but above the second bobbin. Each of the two thread guide flyer arrangements is provided with a first thread-guide eye in the region of the periphery of the associated yarn bobbin, and with a further thread-guide eye substantially in the region of the top edge of the upper yarn bobbin, the thread-guide eyes associated with the lower yarn bobbin being located radially beyond the thread-guide eyes associated with the upper yarn bobbin.
In the ideal case when drawing thread from the two yarn bobbins, an arrangement of this kind ensures that the threads drawn from the two yarn bobbins are properly lifted from the outer surface of the bobbins on the one hand and, on the other hand, do not interfere with one another.
Thus, the eyes of the two thread guide flyer arrangements are disposed such that the threads are lifted from the bobbins disposed one above the other without the threads coming into contact with the sides of the bobbins during the course of feeding the threads to a processing apparatus.
A non-uniform rotational speed of the thread guide flyer occurs when drawing threads overhead from conical cross-wound bobbins. One cause of this is the difference in circumference between the smaller diameter at the top of the creel bobbin and the larger diameter at the bottom of the creel bobbin, it having to be taken into account that the conical shape of the bobbin is necessary in order to draw off the thread overhead, so that the thread can more readily roll on the circumference of the bobbin. A further cause of irregular running of the thread guide flyer is the crossing of the threads which is deposited in an irregularly wound manner due, in most cases, to trouble in a winder arranged in advance of the thread guide flyer arrangement. Rotation of the thread guide flyer is also affected by the snagging of the thread on the periphery of the creel bobbin, which occurs in most cases and which greatly obstructs free rotation of a thread guide flyer.
As a result of the specified causes of irregular rotation of the thread guide flyer, decelerative and accelerative moments are imparted to the thread guide flyer. These forces are effective for varying periods of time according to the mass of the thread guide flyer. Threads which are lifted from the periphery of a cross-wound bobbin by the known thread guide flyer arrangements are never uniformly tensioned and, as a result of this, run with differing tension into a thread processing device disposed beyond the thread guide flyer arrangement. As a result of, for example, greater spinning twist, a piece of thread under lower tension has a tendency immediately to form loops which either directly hinder further processing or which lead to a reduction in the quality of the material during further processing.
An object of the invention is to design a thread guide of the kind described initially, such that uniformity of the rotational speeds of the thread guide flyers or of the pigtail flyer arrangements for the two yarn bobbins (creel bobbins) disposed coaxially one above the other is obtained or ensured when the threads are being drawn off overhead.
A thread guide in accordance with the invention for drawing threads overhead from two yarn bobbins disposed coaxially one above the other comprises a separate thread guide flyer arrangement mounted by means of a respective bearing bushing for each yarn bobbin, the first thread guide flyer arrangement provided for the lower yarn bobbin being mounted between the two yarn bobbins, and the second thread guide flyer arrangement associated with the upper yarn bobbin being also mounted between the two yarn bobbins and in a manner which influences the bearing bushing of the first thread guide flyer arrangement.
In this manner, interaction between the rotational speeds of the two thread guide flyer arrangements is produced, that is to say, the rotational speed of one thread guide flyer arrangement affects the rotational speed of the other thread guide flyer arrangement. In order to utilize the positive effect of a thread guide of this kind to an optimum extent, the two yarn bobbins are mounted such that the two thread guide flyer arrangements rotate in opposite directions when the thread is being drawn off. If, in an arrangement of this kind, one of the two thread guide flyer arrangements seeks to run at a higher speed as a result of the negative causes or influences described above, it is rotated back relatively by the second thread guide flyer arrangement by frictional forces, that it to say, it is prevented from running at a higher speed. As a result of this, the thread guided by means of a thread guide flyer arrangement of this kind cannot become loose or slack and tend to form snarls. The thread always remains taut, since, with respect to the rotational speed, the two thread guide flyer arrangements mutually influence one another or keep one another under control.
The thread guide is accordance with the invention can be used wherever thread is simultaneously drawn off along the common axis of a plurality of yarn bobbins which are disposed coaxially one above the other.
Preferably, the bearing bushings of the two thread guide flyer arrangements are in sliding frictional contact with one another. The bearing bushings can be in the form of simple bearing rings which are mounted one above the other, or in the form of cylindrical bushings which are inserted one within the other and which, if necessary, can also be provided with annular flanges formed thereon.
Preferably, each thread guide flyer arrangement has a substantially radially directed thread guide flyer arm to the outer end of which is connected an axially directed thread guide flyer bar which is provided with at least one thread-guide eye. Preferably, a respective thread-guide eye can be disposed in the region of the periphery of the associated yarn bobbin, and a further thread-guide eye can be disposed substantially in the region of the top edge of the upper yarn bobbin.